NWS discusses ice jam dangers
January 6, 2021
HELENA, Mont. – Damaging floods caused by ice jams are a fact of life along many Montana rivers and streams. The Montana Department of Natural Resources and Conservation (DNRC) would like to remind residents with the start of winter, ice is beginning to form, and the ice jam threat is beginning to rise.
Arin Peters, Senior Service Hydrologist with the National Weather Service Great Falls has advised that the thick ice associated with ice jams forms when the temperatures are consistently low enough for extended periods of time. He also reminded us that it is NEVER safe to walk out onto a frozen river or ice jam. Thermal currents in rivers are unpredictable and ice can become unstable in an instant, leading to injury or drowning.
Traci Sears, Montana National Flood Insurance Program Coordinator, said it's important that residents living near a river or stream have a flood evacuation plan and consider the following steps:
* Purchase flood insurance. In most cases, flood insurance must be purchased 30 days before a flooding event.
* Keep extra drinking water on hand. Flooding can compromise local water systems.
* Shovel or plow snow away from homes and structures.
* Be ready to transport valuables or, where practical, elevate them.
The Montana All-Hazards Weather Monitor web site offers up-to-date information on stream flows and potential flood conditions: http://www.wrh.noaa.gov/byz/state/current.php?wfo=tfx
To learn more about the National Flood Insurance Program, visit. https://www.floodsmart.gov/.
More than 80 percent of ice jams and associated flooding in Montana take place between January and March, with the highest number occurring in March. The most ice jams ever recorded in a single season was 75 in 1996.